Kids Are Crew Members Too!
One sure sign that a TV show has "jumped the shark" is the sudden introduction of a cute little kid. These tots carried news of doom and gloom, just as they do in Gloom in Space, but they often went on to have very successful careers of their own, but characters like Cousin Oliver (Robbie Rist) on The Brady Bunch, Luke (Leonardo DiCaprio) on Growing Pains, and Penny (Janet Jackson) on Good Times couldn't save these shows once they were in decline.
The Kid in science fiction TV and movies doesn't have the same curse attached. In fact, many sci-fi shows start with a kid among the original cast. Since many sci-fi fans were kids themselves before the genre won credibility with blockbuster movies and cult followings of syndicated shows like Star Trek, the inclusion of young characters like Adric and Susan of Doctor Who, Will Robinson of Lost in Space, and Boxey of Battlestar Galactica obviously gave kids a relatable cast member (called an "audience surrogate") so they could see themselves in the interplanetary action.
Older kids also made it into some famous lineups. Wesley Crusher, played by Wil Wheaton (lately of TableTop fame), boarded the rebooted USS Enterprise with a truly impressive of horrifying sweaters when Star Trek: The Next Generation took to the airwaves. Captain Benjamin Sisko of Deep Space Nine also had his son Jake with him on the station. And while he could otherwise be labeled The Farm Boy or The Hero, it only takes a few moments of whining about power converters and Toshi Station to convince viewers that Star Wars' Luke Skywalker is first and foremost a teenager.
An interesting variant on The Kid shows up in Japanese movies. In addition to offering an audience surrogate to young kaiju (monster) fans, a young boy or girl often notices a pattern about the invading creature that would help adults understand it better. Unfortunately, the kid isn't given any credence until they convince a scientist to present their ideas to one of the many intergovernmental panels. In later movies, the Kid even befriends some of the monsters. The rocket-legged giant turtle Gamera even becomes known as "a friend to all Japanese children."